Method of preparing animal litter

ABSTRACT

Animal litter of improved quality is prepared from leafy green vegetable material by a procedure which includes removal of precursors of offensive odor-causing elements. The material is washed, compressed and dehydrated, and contains a sufficient amount of ammonia to preserve a given ph level. The material may also contain an active quantity of chlorophyll and be suitably colored.

United States Patent [1 1 Bickoff et al.

[111 3,747,564 [451 July 24,1973

[ METHOD OF PREPARING ANIMAL LITTER [75] Inventors: Emanuel M. Bickoff;George 0.

Kohler, both of El Cerrito, Calif.

[73] Assignee: The United States of America as represented by theSecretary of Agriculture, Washington, DC.

[22] Filed: Nov. 17, 1971 a 21 Appl. No.: 199,803

2,014,900 9/1935 Lapp 2,126,809 8/1938 Pratt 8/125 3,425,397 2/1969Schulein et al. 119/1 3,059,615 10/1962 Kuceski et al. 119/1 2,649,7598/1953 Gibbs 119/1 2,597,457 5/1952 Cook 119/1 Primary ExaminerLouis G.Mancene Assistant Examiner-James H. Czerwonky Attorney-R. Hoffman et a1.

[57] ABSTRACT Animal litter of improved quality is prepared from leafygreen vegetable material by a procedure which includes removal ofprecursors of offensive odor-causing elements. The material is washed,compressed and dehydrated, and contains a sufficient amount of ammoniato preserve a given ph level. The material may also contain an activequantity of chlorophyll and be suitably colored.

8 Claims, No Drawings METHOD OF PREPARING ANIMAL LITTER A non-exclusive,irrevocable, royalty-free license in the invention herein described,throughout the world for all purposes of the United States Government,with the power to grant sublicenses for such purposes, is hereby grantedto the Government of the United States of Amercia.

DESCRIPTION OF THE INVENTION The invention relates to and has among itsobjects the provision of animal litter of new and improved properties,and novel procedures for preparing it from alfalfa or other leafy greencrops. Further objects of the invention will be evident from thefollowing description wherein parts and percentages are by weight unlessotherwise specified.

In the following description, emphasis is directed to the use of alfalfaas the starting material. Although alfalfa is preferred for the purposesof the invention, ref- ,erence to this particular crop is only by way ofillustration, not limitation. In its broad ambit the invention isapplicable to leafy green crops in general, for example, grasses,lespedeza, clover, alfalfa, and similar conventional forages, and otherleafy green vegetable materials such as lettuce, cabbage, kale, pea orbean vines, celery tops, beet tops, and the like, grown deliberately foranimal feeding or available as wastes or by-products from food packingor processing establishments.

For some time, clay, sawdust, straw, choppedpaper,

and the like have been usedas a litter to keep animal wastes in arelatively dry condition until disposal is possible. However, materialsof this type have various disadvantages. They are light in color andthus afford no disguisingor masking effect. Also, they exhibit poorodor-absorbing properties so that when waste is deposited thereon by apet or other animal, the litter must be quickly replaced to avoidfouling the atmosphere of the household.

More recently, dried alfalfa pellets have been introduced for use asanimal litter. This product is made by dehydrating green alfalfa in arotary kiln or other conventional drier, and then pelletizingthe driedmaterial. The product in question is superior to such litters as clay,straw, sawdust, paper, etc. because it has better moisture and odorabsorption properties and its content of chlorophyll serves as adeodorizer of animal waste deposited thereon. Moreover, the product hasa dark color so that it acts to mask or camouflage fecal matter.

Although pelletized dehydrated alfalfa or other leafy material possessescertain advantages as notedabove, it suffers from certain disadvantages.Noteworthy among these is that it exhibits a strong characteristic odorwhich many persons find repellent. Because of this odor problem thecommercial success of the product has been limited.

A primary object of the invention is the provision of means forobviating the problem outlined above. In particular, the inventionprovides procedures for preparing animal litter which-though made fromleafy material-is essentially. free from the characteristic odorexhibited by dehydrated leafy material. The litter prepared inaccordance with the invention not only obviates a problem of the priorart products, but also retains the advantages of the known productsprepared from alfalfaand other leafy crops. In particular, the productsof the invention have a dark color so that they are effective in maskingor camouflaging animal wastes deposited thereon. They display a highmoisture absorption so that liquidous wastes are absorbed and retainedtherein. They contain chlorophyll in adequate amount to suppress anddestroy odors emanating from animal wastes. They are edible in the sensethat if a pet or other animal should ingest some of the product, no harmwill result.

A critical feature of the invention is that the green alfalfa or otherleafy green material, prior to drying, is subjected to at least onecycle of pressing and washing with water. This procedure causes theremovalof certain substances which may be referred to as precursors ofoffensive odor-causing elements. In other words, the process of theinvention removes substances which normally wouldgive rise toundesirable odorous elements. This situation is further explained asfollows:

It is well known that when alfalfa is in a moist (green) state, itexhibits a mild and pleasant odor. When, however, the alfalfa issubjected to conventional dehydration, a rank, unpleasant odor isdeveloped in the product. In sum, certain substances of unknown. naturewithin the plant material act as odor precursors in that the applicationof dehydrating conditions causes chemical changeswhereby theseprecursors, which have little or no odor, are converted into elementswhich exhibit the strongand unpleasant aroma. However, by the proceduresof the invention, this undesired effect is avoided because theodorprecurso'rs are removed prior to application of the dehydrationstep.

A further advantage of the invention is that it causes removal of sugarsfrom the alfalfa material. As a result, the product is essentiallybiologically inert; that is, it is a poor medium for the growth of moldsand other microorganisms. Thus, whenthe product is moistened--as by.deposition of urine thereon--little if any fermentation or mold growthtakes place. In contrast, products which retain their naturalsugarcontent will ferment rapidly when moistened, whereby offensive andnoxious odors are produced.

The practice of the invention is next described in some detail, havingreference to alfalfa by way of example.

In usual farming practice, alfalfa is chopped as it is harvested; thisconventional chopped green plant material is the starting material ofchoice for the process of the invention.

I. The green alfalfa material is de-juiced by passing it through a presswhichmay take the form, for example,

of a set of conventional sugarcane rolls. Other devices which may beused for the de-juicing are screw presses or expellers. In thisde-juicing operation, there is produced a juice fraction and apress-cake of the solid alfalfa material. In this operation, most of theodor precursors present in the original material are transferred to thejuice fraction, which is discarded.

II. The press-cake is next washed with water, whereby to extract afurther portion of the odor precursors to the wash water, the latterbeing discarded.

To secure good contact between the alfalfa material and water, it ispreferred to break up the press-cake into small particles. For example,the press-cake is introduced into a tank with about 0.5 to 10 times itsweight of water and agitation is applied-as by the use of a power-drivenpropeller-to break up the presscake and mix the resulting particles withthe aqueous phase. Following this, the water and alfalfa material areseparated as by applying screening, centrifugation, decanting or thelike. Alternatively, the mixture of water and alfalfa material, withoutany separation step, is directed to the next operation.

Ill. The alfalfa material from Step II is re-pressed as in Step I tode-water it, a further allotment of odor precursors being eliminatedwith the press water.

IV. The press-cake from Step III is then dehydrated by conventionalmeans, for example, in a rotary kiln supplied with a draft of hotgaseous products of combustion.

V. Preferably, the dehydrated material is compressed into pellets orother particulate form. Typically, pellets having a size of aboutone-sixteenth to one-fourth inch are formed.

It is within the purview of the invention to apply the above-describedwashing and pressing steps more than once to attain a product ofparticular low odor value. For example, the press-cake from Step III maybe rewashed and re-pressed before it is subjected to dehydration (StepIV).

Prior to the de-juicing operation (Step I), the green alfalfa may betreated with ammonia to preserve its chlorophyll content at a highlevel. Since chlorophyll is responsible for the products excellentdeodorizing properties, a high concentration, therefore, is obviouslydesired. Where this modification of the invention is applied, enoughammonia is added to give the alfalfa a pH of at least 7, preferablyabout 8.0 8.5. (The natural pH of alfalfa is 5.5 to 6.5.) Ammoniation ismost easily effected by adding the anhydrous gas from a commercial tank.Although addition of ammonia in the gaseous form offers the mostconvenience, one may add it in the form of aqueous solutions. Thus forthe purposes of the invention, aqua ammonia may be considered theequivalent of gaseous ammonia. Where ammoniation is used it is preferredto apply a neutralization step at some stage prior to dehydration. Forthe purpose, one can use any non-toxic acid such as sulphuric,hydrochloric, phosphoric, citric, or the like in a quantity sufficientto restore the alfalfa material to about its natural pI-I.

Although the litter in accordance with the invention can be used bothindoors and outdoors, its main advantage is to the domestic pet ownerfor indoor use. Thus, where the litter is confined to the household, theabsence of the offensive dried alfalfa odor is most appreciated.

EXAMPLE product of the invention.

As a control, a sample of the original alfalfa was also dehydrated.

Tests were conducted to determine the water absorption characteristicsof the two materials. It was found that the product of the inventionwould absorb 36% more water than the dehydrated alfalfa (control).

It was also noted that the product of the invention had a mild pleasantodor whereas the control sample had a strong unpleasant odorcharacteristic of dried alfalfa.

Urine was added to each of the materials in the proportion of 1 ml.urine per grams of material. The resulting samples were allowed to standat room temperature in an open container. After the third day bothsamples were smelled. The control sample exhibited a strong unpleasantodor; the product of the invention exhibited a much weaker odor. After 3weeks it was observed that the control sample had a whitish mold growingon its surface. The product of the invention did not evidence any moldgrowth.

Having thus described the invention, what is claimed 1. A process forconverting leafy green vegetative material into animal litter which isessentially free from the characteristic odor of dehydrated leafyvegetative material, which comprises a. mixing a sufficient amount ofammonia into the vegetative material to preserve a given ph level,

b. pressing leafy green vegetative material to remove the juice and toobtain a press-cake of solid fibrous material,

c. washing the said press-cake,

cl. pressing the washed material to remove occluded wash water,

e. dehydrating the press-cake from Step ((1), and

f. compressing the dehydrated material into particles suitable for useas animal litter.

2. The process of claim 1 wherein the leafy green vegetative material isfresh green alfalfa.

3. A process for converting alfalfa into animal litter which isessentially free from the characteristic odor of dehydrated alfalfa,which process comprises a. mixing a sufficient amount of ammonia intothe vegetative material to preserve a given ph level,

b. pressing fresh green alfalfa to remove the juice and to obtain apress-cake of fibrous material,

0. agitating the press-cake with added water for a sufficient period oftime to break up the press-cake and mixing the resulting particles withthe water,

d. pressing the resulting wet mass to remove oc- I cluded water, and

e. dehydrating the resulting press-cake.

4. The process of claim 3 wherein the dehydrated material is compressedinto pellets.

5. The process of claim 3 wherein, prior to dehydration, the press-cakefrom step (d) is re-agitated with added water and the resulting wet massis re-pressed to remove occluded water.

6. A composition for use as an animal litter comprising a particulate,compressed, washed, and dehydrated,

chlorophyll-containing leafy vegetative material char-- acterized by theproperties of readily absorbing liquids, having a color suitable formasking animal wastes deposited in the litter, including a sufficientactive quantity of chlorophyll therein to suppress and destroy odorsemanating from said wastes, and also including a sufficient quantity ofammonia to preserve a given ph level, said washed composition beingessentially free from the characteristic odor of dehydrated leafyvegetative material.

7. The composition of claim 6 wherein the vegetative material isalfalfa.

8. The composition of claim 6 which has the additional characteristic ofbeing essentially free from sugars.

2. The process of claim 1 wherein the leafy green vegetative material isfresh green alfalfa.
 3. A process for converting alfalfa into animallitter which is essentially free from the characteristic odor ofdehydrated alfalfa, which process comprises -a. mixing a sufficientamount of ammonia into the vegetative material to preserve a given phlevel, b. pressing fresh green alfalfa to remove the juice and to obtaina press-cake of fibrous material, c. agitating the press-cake with addedwater for a sufficient period of time to break up the press-cake andmixing the resulting particles with the water, d. pressing the resultingwet mass to remove occluded water, and e. dehydrating the resultingpress-cake.
 4. The process of claim 3 wherein the dehydrated material iscompressed into pellets.
 5. The process of claim 3 wherein, prior todehydration, the press-cake from step (d) is re-agitated with addedwater and the resulting wet mass is re-pressed to remove occluded water.6. A composition for use as an animal litter comprising a particulate,compressed, washed, and dehydrated, chlorophyll-containing leafyvegetative material characterized by the properties of readily absorbingliquids, having a color suitable for masking animal wastes deposited inthe litter, including a sufficient active quantity of chlorophylltherein to suppress and destroy odors emanating from said wastes, andalso including a sufficient quantity of ammonia to preserve a given phlevel, said washed composition being essentially free from thecharacteristic odor of dehydrated leafy vegetative material.
 7. Thecomposition of claim 6 wherein the vegetative material is alfalfa. 8.The composition of claim 6 which has the additional characteristic ofbeing essentially free from sugars.